从废稀土荧光粉回收稀土

稀土荧光粉广泛应用于发光材料行业,并且用量每年都在不断增长,同时产生的废旧稀土荧光粉也越来越多.因此,从中回收稀土不仅有利于保护环境,而且有利于资源的充分利用.物理方法难以从废旧稀土荧光粉中分离得到高纯度单一稀土,化学方法则可以获得单一高纯稀土.而它的瓶颈在于浸出和分离的高效性及经济性.本文对废稀土荧光粉回收稀土技术的现状进行了分析,认为已具有从废旧稀土荧光粉中提取单一、高纯稀土的成套新技术.     

Global rare earth resources and scenarios of future rare earth industry

It is known to all that China is abundant in rare earth resources.But rare earth deposits are really not that rare in the earth crust.In the five continents,i.e.Asia,Europe,Australia,North and South America,and Africa,there are about thirty four countries found to have rare earth deposits;Brazil might surpass China and rank the first in rare earth deposits.At present,investment in rare earth production was surged,there have been about 200 projects,and the total production for 25 of them would be more than 170 thousand tons after 2015,a multi-supply system on rare earths is being established worldwide.Cautions on the investment of rare earth production are involved.     

电感耦合等离子质谱法测定离子型稀土原矿中离子相稀土总量

采用电感耦合等离子质谱法(ICP-MS)直接测定离子型稀土原矿中离子相稀土总量,实验对浸取溶液、浸取溶液的浓度及用量、被测元素的同位素、样品酸度、内标元素、仪器的最佳工作参数进行了选择,建立了优化分析条件.单一元素标准加入的回收率为95%~105%,离子相稀土总量回收率为98.4%,相对标准偏差小于5%,测定范围为:0.010%~0.50%.方法准确可靠,操作简单,精密度和准确度都能满足分析要求.     

稀土出口价格与稀土储备

稀土出口价格和稀土储备是稀土研究的两个重要问题.从稀土的应用价值、相对稀缺性、生产的环境代价以及稀土供给的垄断特征,分析我国稀土出口应该有一个比较高的价格;从供求关系、市场结构、储备特征、储备对需求弹性和供给弹性的影响,分析储备对稀土出口价格的影响方向和影响效果;从储备的作用和稀土产业的未来发展目标,提出稀土储备的主要目的和方式.研究结果表明：稀土出口所形成的市场结构使我们丧失了稀土出口的议价能力;稀土国家储备在短期会对稀土出口价格提升产生一定的效果,但长期效果有限;稀土储备的主要目的应该是促进稀土应用产业的发展,并以稀土原矿（稀土资源）储备为主.     

世界稀土资源供需现状与中国产业政策研究

稀土资源已经成为世界现代工业化建设中不可或缺的因素,有着重要的战略价值.根据世界稀土资源的分布现状及世界稀土资源的供求状况,并结合我国稀土资源开采利用中存在的盲目滥采、落后开采、生态环境破坏严重、稀土产品深加工和后处理工艺技术水平低等问题,分析了我国进行稀土资源调控的政策方向,即建立稀土资源国家战略储备机制、建立并健全稀土期货交易市场、加强稀土产业政策的执行力度、谨慎制订稀土出口配额以及对稀土勘探、开采、分离、冶炼、深加工以及出口等设立专题分别进行重点研究与攻关,对我国未来稀土产业健康发展具有重要意义.      

等离子喷涂稀土六铝酸盐热障涂层

采用固相法合成了三种稀土六铝酸盐陶瓷粉末即NdMgAl11O19(NMA),SmMgAl11O19(SMA)和GdMgAl11O19(GMA)。采用大气等离子喷涂方法制备了这三种陶瓷涂层。采用扫描电镜(SEM)、X射线衍射(XRD)和维氏硬度计对涂层进行了表征。结果表明,采用等离子喷涂方法制备的涂层具有典型的多孔结构,陶瓷的熔化状态良好,涂层与金属粘结层之间结合致密。MgO掺杂的稀土六铝酸盐在等离子喷涂过程中发生部分分解,涂层结晶不完全。此外,随着稀土离子半径的减小,喷涂后涂层硬度逐步增加。     

Transformations in rare earth metals

The crystal structures of rare earth metals and intrarare earth alloys are described and studies of the phase transformations in these metals are surveyed. Comparison is made with similar transformations in other alloy systems. Knowledge of the thermodynamics, kinetics and mechanisms of transformations in the rare earths is assessed and directions for future work are suggested. This paper is based on a presentation made at a symposium on “Phase Transformations in Less Common Metals: A Dialogue,” held at the Fall Meeting in Cleveland on October 16, 1972, under the sponsorship of the Phase Transformations Activity, Materials Science Division, American Society for Metals.     

从离子型稀土矿浸取液中提取稀土的技术现状与展望

综述了沉淀法、沉淀浮选法、溶剂萃取法、离子交换法、液膜分离法等方法从离子型稀土矿浸取液中提取稀土的技术研究进展.在提取稀土的各种方法中,碳酸沉淀法因成功实现了稀土母液无毒化,改善了矿山生态环境等特点,在今后很长的一段时期内仍将是从离子型稀土矿浸取液中提取稀土的主要方法.但溶剂萃取法由于可直接生产出可溶性稀土盐或稀土料液,还能对稀土进行萃取分组以制备稀土分组产品,从而改变了稀土矿山一直以来只能生产混合氧化稀土的不利局面,提高了矿山的经济效益等特点,且符合绿色化学提取稀土资源的要求,将会有很好的发展前景.     

还原酸浸对废旧稀土荧光粉中稀土提取的影响

为解决废旧稀土荧光粉中高价态Ce、Tb氧化物浸出困难的难题, 在碱熔焙烧预处理的研究基础上, 采用还原酸浸的方法, 以抗坏血酸作为还原剂, 来提高废旧稀土荧光粉的稀土浸出率。实验表明:在HCl浓度为4 mol/L, HCl与水洗渣液固比(单位为:mL/g, 下同)为10:1、抗坏血酸用量为10%、温度为338 K、时间为120 min、搅拌转速为650 r/min的条件下, 稀土浸出率可以达到98%以上。      

ICP-AES法测定稀土(镁)硅铁中La和Ce

采用ICP AES法测定稀土(镁)硅铁中La和Ce含量,并对样品的溶解方法、基体及共存元素的影响、分析谱线进行了研究。方法简便、快速,精密度和准确度较好。     

Element migration and phase distribution characteristics during crystallization of rare earth phase in rare earth slag

The crystallization experiment of molten rare earth (RE) slag under different cooling rates was carried out. The characteristics of element migration and phase distribution during RE phase crystallization were studied by using different equipment. The experimental results show that there are two RE phases in the RE slag, namely (Ca, Ce, La)₅(SiO₄)₆F and (Ca,Ce,La,Mg)₃(Ti,Al,Nb)₂O₇. During the cooling crystallization process of molten RE slag, Ca and P elements in the RE phase of (Ca,Ce,La)₅(SiO₄)₆F migrate from inside to outside, and finally gather at the outer edge of the phase to form phase Ca₃(PO₄)₂. The RE phase (Ca,Ce,La)₅(SiO₄)₆F is distributed inside the furnace-cooled slag, and the RE phase (Ca,Ce,La,Mg)₃(Ti,Al,Nb)₂O₇ is distributed in the surface layer of the furnace-cooled slag. And based on the phase distribution characteristics, the central hollowing method is proposed to realize the preliminary enrichment of valuable elements Ti, Nb and RE in RE slag.     

田菁胶助浸低品位风化壳淋积型稀土矿研究

针对低品位风化壳淋积型稀土矿渗透性存在的问题,采用田菁胶作助浸剂,利用其促渗性能来提高风化壳淋积型稀土矿浸取效率,通过试验考查了田菁胶浓度、浸取剂浓度、浸取流速、浸取固液比对稀土浸取效果的影响.结果表明,田菁胶助浸使稀土的浸取率由87.05 %提高至94.17 %,同时还减少32.56 %浸取剂用量,有效地提高了风化壳淋积型稀土矿的浸取效率.      

A novel process for recovering rare earth from weathered black earth

A novel process for recovering rare-earth (RE) elements from weathered-black-earth slime is developed. This process involves the initial removal of Mn by reduction leaching using SO₂ followed by ammonium chloride roasting of the residual solids from the leaching process. The controlled roasting selectively converts RE oxides to water-soluble RE chlorides. The roasted materials are then dispersed in warm water (75 °C) to extract RE, while water-insoluble iron oxides remain in gangue sludge, minimizing iron impurities in final RE products and hence simplifying the purification process. Leadchloride precipitates are obtained by cooling the leachate to −10 °C, and RE is recovered using oxalic acid precipitation. With this new process, a product of 92 pct purity at a RE recovery greater than 65 pct is obtained. In addition, Mn and Pb are recovered as by-products, with a recovery of 64 and 54 pct, respectively. The effect of operating variables on RE recovery is examined and the process chemistry described.     

电感耦合等离子体质谱法测定离子吸附型稀土矿中全相稀土总量

采用硝酸-氢氟酸-高氯酸混酸溶解试样,以电感耦合等离子体质谱法(ICP-MS)对试样溶解液进行测定,提出了以ICP-MS测定离子吸附型稀土矿中全相稀土总量的方法。对氢氟酸用量和测定液中硝酸的含量进行了考察,最终确定氢氟酸用量为5.0mL,测定液介质为体积分数为2%的硝酸。在优化的仪器条件下,15种单一稀土元素校准曲线的线性相关系数均大于0.9999,方法检出限为2.4μg/g。采用实验方法对稀土矿石国家标准物质GBW07158、GBW07160、GBW07161(用于标样制定的样品均采自江西省龙南离子吸附型稀土矿区)中的稀土总量进行测定,测定结果与认定值基本一致。将实验方法应用于稀土矿石国家标准物质GBW07159、GBW07160与离子吸附型稀土矿实际试样中稀土总量的测定,测得结果的相对标准偏差(RSD,n=11)为1.7%~3.1%。     

碱熔预处理对废旧稀土荧光粉中稀土提取的影响

针对废旧稀土荧光粉特性,采用高温碱熔与酸浸相结合的方法处理废旧稀土荧光粉,考察碱熔温度、氢氧化钠用量、碱熔时间对稀土浸出率和铝回收率的影响,并对碱熔过程中的物相及形貌变化进行分析.结果表明,在碱熔温度为1050℃、氢氧化钠与废粉质量比为2.5∶1、碱熔时间为2 h 条件下,其稀土浸出率可达98%以上,铝回收率可达98%.通过对碱熔产物物相和形貌分析表明,废粉晶体结构被有效破坏,其中稀土以稀土氧化物形式存在,碱熔产物变成无定型云絮状.     

Non-ammonia enrichment of rare earth by magnesium oxide from rare earth leaching liquor in magnesium salt system

In order to solve the problem of ammonia-nitrogen pollution in the enrichment process of the ionadsorption type rare earth ore,the technology of non-ammonia precipitation with magnesium oxide precipitant was carried out.It is determined that the rare earth precipitation efficiency is 99.6% and the purity of rare earth concentrates is only 85.89 wt%under the optimum precipitation conditions.And the contents of MgO,SO_3 and Al_2O_3 in the rare earth concentrates are 5.12 wt%,6.77 wt%and 1.78 wt%,respectively.Furthermore,the thermo-decomposition process of precipitates was investigated by TGDSC,XRD and FI-IR.The thermal decomposition process consists of two stages:the dehydration of rare earth hydroxide and alkaline rare earth sulfate within 900 ℃ and the thermal decomposition of RE_2O_2SO_4 at 900-1300 ℃.Therefore,a high-temperature calcinations method for removing SO_3 from precipitates is proposed.When the precipitates are calcined at 1300 ℃ for 2 h,the rare earth concentrates with a purity of 92.03 wt%can be acquired.Moreover,the content of SO_3 in the concentrate is only 0.46 wt%.In the MgO precipitation and high-temperature calcinations process,the raw material cost is low and the quality of rare earth concentrates is acceptable.It could have great significance for nonammonia enrichment of rare earth from the rare earth leaching liquor,and finally solve the problem of ammonia nitrogen in the extraction process of the ion-adsorption type rare earth ore within magnesium salt system.     

电感耦合等离子体质谱法测定离子型稀土矿中离子相稀土总量及分量

采用硫酸铵溶液提取离子型稀土原矿试样中离子相稀土,以硫酸铵溶液为基体配制校准系列溶液,建立了电感耦合等离子体质谱法(ICP-MS)测定样品溶液中离子相稀土总量及分量的方法。实验表明:对于10.00 g离子型稀土矿试样,加入100 mL 50 g/L硫酸铵溶液振荡15 min后放置30 min可有效提取出离子相稀土;采用5.0 g/L硫酸铵溶液进行校准系列溶液的基体匹配,选择¹⁰³Rh-¹⁸⁵Re双内标可有效校正硫酸铵的基体效应及仪器信号的漂移影响;选择合适的同位素消除了可能存在的质谱干扰。在最佳条件下进行测定,15个稀土元素的校准曲线在10.0~100.0 μg/L范围内线性相关系数均大于0.999 91,方法检出限在0.10~0.66 μg/g之间。方法应用于不同离子型稀土矿区中离子相稀土总量及分量的测定,结果与电感耦合等离子体原子发射光谱法(ICP-AES)一致,相对标准偏差(RSD,n=11)在1.0%~5.2%之间,回收率在98%~104%之间。     

Study on rare earth electrolyte of SDC

The grain boundaries of polycrystalline oxygen ion conductors presented a blocking effect on the oxygen ionic transport across them.It was found that the apparent specific grain boundary conductivity was 2-3 orders of magnitude lower than the bulk conductivity in the temperature range of 200-500 ℃ for normal purity Ce0.85Sm0.15O1.925(SDC)with an average grain size of 320-580 nm.The apparent specific grain boundary conductivity increased with decreasing average grain size.It was found that the space charge potential was nearly independent of grain size,and the reason was analyzed.The increase of the conduction path width was resportsible for the increase in the apparent specific grain boundary conductivity.